In a residential room, bacteria, virus and the like such as serratia and bacillus are floating while unpleasant odors are attached to curtains, clothes and the like hung in the room. An air purifier is provided in such a room in order to clean the air in the room. The air purifier described in Patent Document 1 includes dielectrics that generate H+(H2O)n of a positive ion and O2−(H2O)n of a negative ion, and an air blower that discharges H+(H2O)n and O2−(H2O)n generated by the dielectrics in a room.
The air purifier generates H+(H2O)n and O2−(H2O)n at the same time to produce hydrogen peroxide H2O2 or hydroxyl radical (.OH), which are active species, by chemical reaction. Since the hydrogen peroxide H2O2 or hydroxyl radical (.OH) shows extremely high activity, floating bacteria may be decomposed and eliminated by discharging the hydrogen peroxide H2O2 or hydroxyl radical (.OH) in the air in a room.
In recent years, a technique of purifying the air in a residential space by charging water molecules in the air with positive (plus) and/or negative (minus) ions has widely been used. For example, an ion generating apparatus represented by an air purifier is provided with an ion generator that generates positive and negative ions along the path of the inside air-flowing path to discharge the generated ions to the outside space together with the air.
In a residential space, the ions charging the water molecules in the clean air inactivates floating particles and killing floating bacteria while degenerating odor components to purify the air in the entire residential space.
A standard ion generator generates corona discharge to generate positive and negative ions by applying a driving voltage, which is a high and alternating voltage, between a needle electrode and an opposite electrode or between a discharge electrode and a dielectric electrode.
When, however, the ion generator is used for a prolonged period and thus the discharge electrode is worn out due to sputter evaporation associated with corona discharge, or when foreign materials such as chemicals, dust and the like are cumulatively attached to the discharge electrode, decrease in the amount of generated ions cannot be avoided. Here, it is required to detect ions in the air in order to notify the user that the ion generator needs maintenance.
To address the above, for example, Patent Document 2 discloses an ion sensor provided with an electrode that collects ions in the air to detect ions.
In recent years, a technique of purifying the air in a residential space by charging water molecules in the air with positive (plus) and/or negative (minus) ions has widely been used. For example, an ion generating apparatus represented by an air purifier is provided with an ion generator that generates positive and negative ions along the path of the inside air-flowing path to discharge the generated ions to the outside space together with the air.
In a residential space, the ions charging the water molecules in the clean air inactivates floating particles and killing floating bacteria while denaturing odor components to purify the air in the entire residential space.
A standard ion generator causes corona discharge to generate positive and negative ions by applying a driving voltage, which is a high and alternating voltage, between a needle electrode and an opposite electrode or between a discharge electrode and a dielectric electrode.
For example, with the air purifier disclosed in Patent Document 1, the concentration of ions discharged with the air corresponds to 1000 to 2000/cm3 in a normal room. Thus, a certain level of sterilization effects on bacteria such as serratia and bacillus may be expected. However, the effects of eliminating virus and of eliminating odor attached to curtains, clothes and the like are small. An ion generating apparatus that can increase the ion concentration in a room has been desired.
Moreover, since one ion generator may generate only a limited amount of ions, an attempt has been made in which a plurality of ion generators are arranged in an air-flowing path to increase the amount of generated ions.    [Patent Document 1] Japanese Patent Publication No. 3770784    [Patent Document 2] Japanese Patent Application Laid-open No. 2004-3885